The arguments are over; the rhetoric is done. Now America's deeply divided Supreme Court must decide whether President Obama's signature achievement should stand, fall, or be largely struck down.

Court drawing of SCOTUS session (Reuters)

It comes down to this: a fundamental argument over the meaning of liberty, and the extent of Federal power. And the future of the Affordable Care Act hangs perilously on its outcome. After three days, and six hours of oral arguments at the US Supreme Court, it's still by no means clear how the nine justices will rule. There's been some tough questions for the administration's lawyers, leaving liberals feeling rattled: but whatever the outcome, the future of healthcare will be pivotal in the run up to November's election.

The justices have now retired to their chambers, for some three months of deliberation: they're not expected to rule until the Court's session ends in June. At issue on day three - whether the law could survive at all if the judges decide to strike down the very heart of the reforms: the requirement that all Americans must buy health insurance or pay a penalty. They also heard arguments on another provision; requring states to expand the Medicare scheme to millions on low incomes who are currently uninsured.

It's a choice between a wrecking operation...or a salvage job. Justice Ruth Bader Ginsberg

Throughout this historic session, the justices have been divided along ideological lines, with one or two notable exceptions. Justice Antonin Scalia insisted the fate of the entire act hinged on the individual mandate requirement: "If you take the heart out of the statute, the statute is gone", he said, arguing that the Senate would never have passed the law without that key provision. Liberal justice Ruth Bader Ginsberg depicted it as a "choice between a wrecking operation, which is what you are requesting, or a salvage job. And the more conservative approach would be salvage, rather than throwing out everything."

And from Justice Kennedy, who's sometimes sided with the liberal wing, a pertinent question about cash. The 10 year cost of the reforms was meant to be offset partly by new income from the individual mandate, the rest from the expansion of Medicare, he said. If the mandate was ruled invalid, how would that hundreds of billions of dollars shortfall be plugged? He argued that it would be a more extreme use of judicial power "if one...provision was stricken and the others remained, to impose a risk on insurance companies that Congress had never intended."

Divided Court

Chief Justice John Roberts was harder to read on this one: noting dryly that it was impossible to discern what Congress had really wanted, given all the horse-trading and compromises that they'd made. "That's just an inquiry you can't carry out", he said. Lawyers for the White House appealed to the bench to let the Congress, and the people decide.

As for expanding Medicaid provision, the split was clearer. The 26 states objecting to Obamacare said they were effectively being forced to spend money on a policy they didn't agree with. Scalia called that an offer they couldn't refuse, but to Justice Elena Kagan, that was a strange argument. "It's just a boatload of federal money for you to take and spend on poor people's healthcare. It doesn't sound coercive to me, I have to tell you."

And that was it: with a final rhetorical flourish from lawyers on both sides. Solicitor General Donald Verrilli appealed for his definition of freedom, for the millions of Americans suffering chronic conditions like heart disease and breast cancer: for them, he said, Obamacare meant freedom from financial harm caused by the huge cost of their care, and a freedom from the shackles of their condition. For Paul Clement, representing the opponents of the law, "it's a very funny conception of liberty that forces somebody to purchase an insurance policy whether they want to or not."

It's a very funny conception of liberty that forces somebody to purchase an insurance policy. Paul Clement, lawyer fighting the Act

Now the focus turns from the law, to politics. For the White House, a battle to fight against the idea that it's already lost the battle, and instead to mount an aggressive defence of the most popular provisions, that would be lost if the law were to be struck down. At the moment, they're insisting there's no contingency plan: as spokesman Josh Earnest insisted: "We're focused on implementing the law."

Risky fight

But some Democrats are openly thinking the unthinkable: that this most hard-fought achievement might be lost. For strategist James Carville, that might not be such a bad thing: arguing that everything that goes wrong with the health care system could then be blamed on the Republicans. A court decision against Obama, he claimed, "will be the best thing that has ever happened to the Democratic Party."

While not going quite that far, other liberal activists believe they could use it as a rallying cry to galvanise supporters. The lobby group Protect Your Care told the Washington Post: "You'd have a 5-4 court, in clearly a partisan political decision, striking down not just President Obama's biggest legislative accomplishment, but also the biggest progressive legislation since LBJ." A somewhat risky strategy, to say the least, when the president is already struggling to win over popular support for the reforms.

It's a mixed prospect for the Republicans, too. Virginia Governor Bob McDonnell sounded triumphant, in the New York Times: "A victory in court would say that a trend towards big government solutions out of Washington has a limit, and the biggest accomplishment of the Obama administration is unconstitutional." Sounds bad, whichever way you say it. But remember that Mitt Romney, putative Republican nominee, pioneered his very own individual mandate system through Massachussetts, when he was Governor: not quite so easy, then, for him to crow over the death of a near identical federal scheme.

It's been a historic week: a week when the three branches of America's government have clashed in a debate that goes to the very heart of America's values. Freedom from the compulsion to buy health insurance, or the freedom to benefit from affordable care? Now it's down to those nine justices, and the most important decision of their lives. For the millions of Americans whose healthcare hangs in the balance, a new spin on that old slogan: 'Give me liberty, or give me death'; indeed.

Felicity Spector writes about US politics for Channel 4 News